Communication networks comprising hybrid fiber coaxial (HFC) transmission lines are being used extensively because of their ability to provide a wide range of services from broadcast entertainment, high speed internet access, interactive multimedia and sophisticated telephony services. Provision of high quality service requires that power supplies and energy sources be located in the field close to the HFC network. Since the number of available sites for locations is limited power equipment, suitable for several HFC sites, must be collocated, to limit the total number of needed sites.
Power equipment and electronic equipment, both switching and processing, are fundamental components of communication networks. While they differ in form and function they all universally dissipate heat which must be accommodated by some form of heat exchange. Often the power equipment, as indicated, includes power supplies and batteries. Batteries make the additional requirement of accommodating the hydrogen gases that are exhausted.
In large spacious enclosures such heat may be readily dissipated in a plenum. Heat absorbed by the air plenum is transferred to heat exchangers by providing ample space for large quantities of air to circulate about a heat sink. The system generally operates because the enclosure is generally well positioned and sufficiently large in size to easily accommodate the desired heat transfer so that heat may be safely dissipated from the equipment.
Spacious arrangements that readily permit large heat transfers from heat generating equipment are not always available however. Government regulations often restrict the size and location of containers containing the needed electrical equipment. In many cases the equipment housing must be out of or nearly out of public view or perception and, hence, available space for the equipment and air plenum is very constrained.
The heat dissipating and hydrogen outgassing plenum volume as constrained by these requirements may be unrelated to the equipment heat dissipation needs. These may be location requirements; size and shape requirements and other requirements related to neighborhood appearance and esthetics.
It seems desirable, for these reasons, to locate such a container under ground. Several problems arise from using an underground location. These problems include, as indicated above, heat dissipation of the enclosed power supplies, removal of hydrogen gasses generated by the enclosed batteries and the intrusion of water into the container. The restricted size alone may not accommodate the heat dissipation requirements of the equipment. As such the operating lifetime of the equipment is severely reduced.
It is a dual prerequisite to conform to these regulatory requirements and to engineering requirements to effectively provide for outgassing and heat dissipation of the equipment.